1. Technical Field
The invention relates to electric hair trimmers, and more particularly to cutting head assemblies for use with electric hair trimmers.
2. Related Prior Art
It is generally known to provide an electric hair trimmer with a cutting head assembly which can be releasably and operably mounted on the trimmer. The provision of a releasable cutting head assembly facilitates the cleaning and replacement of the cutting head assembly. Typically, an electric hair trimmer for use with a releaseable cutting head assembly includes a body and a spring-loaded, pivotable support tongue which is fixed to one end of the clipper body. The support tongue is engageable with the associated cutting head assembly to hold the cutting head assembly in an operable position on the clipper body. When the tongue is pivoted forwardly to an "open" position away from the body, the cutting head assembly can be placed on the tongue. When the tongue is snapped into a "closed" position against the clipper body, the cutting head assembly is held securely against the clipper body.
Two examples of releaseable cutting head assemblies for use in association with a hair trimmer are illustrated respectively in U.S. Pat. No. 2,182,597 which issued to Oster on Dec. 5, 1939, and in U.S. Pat. No. 2,928,171 which issued to Oster on Mar. 15, 1960. The above-listed U.S. Patents illustrate cutting head assemblies which include a tongue-receiving socket for mounting the assembly on an associated support tongue.
Under some circumstances, it may be desirable for cutting head assemblies to be interchangable between various electric clippers. Some cutting head assemblies cannot be interchangably mounted on some trimmers, however, because some trimmers provide a support tongue which has a specific configuration and which can only releasably engage a particular cutting head assembly having a correspondingly configured tongue-receiving socket, but which cannot releasably engage a cutting head assembly having a differently configured tongue-receiving socket.
For example, one type of support tongue known in the prior art has a relatively uniform thickness across the width of the tongue and has a generally planar bottom surface. Another type of support tongue known in the prior art has a varying thickness across the width of the tongue and is characterized by two ribs which are disposed on the bottom surface of the tongue and which extend downwardly. A cutting head assembly configured for use in association with a trimmer having the first type of support tongue, i.e. a tongue having a generally planar lower surface, cannot be used interchangeably with a trimmer having a support tongue including a ribbed bottom surface because the downwardly extending ribs prevent engagement of the tongue with the tongue-receiving socket.